| Abstract No.: | B-B2073 |
| Country: | Canada |
| | |
| Title: | CONNEXIN32 EXPRESSION IS UNDER HORMONAL CONTROL IN THE ADULT FEMALE CENTRAL NERVOUS SYSTEM |
| | |
| Authors/Affiliations: | 1 Ashleigh McLean*; 1 Stephanie Fowler; 2 Siba Haykal; 3 Andrea Hebb; 1 Steffany Bennett;
3 Dalhousie, Halifax, NS, Canada; 1 University of Ottawa, ON, Canada; 3 University of Toronto, ON, Canada
|
| | |
| Content: | Objectives: Connexin32 (Cx32) is expressed by mature oligodendrocytes and a subset of early oligodendrocyte progenitor cells in the adult male murine central nervous system. Here we establish that Cx32 is under hormonal control in adult female C57BL/6 mice.
Materials and methods: To determine expression levels over the estrous cycle, the hippocampus and the T11-T13 region of spinal cord were dissected from females during estrus, metestrus/diestrus, and proestrus. mRNA was quantified using qPCR. Perfused tissue was sectioned and Cx32 was visualized by immunofluorescence. Cell types were identified by colabelling with antigenic lineage markers for mature oligodendrocytes and early oligodendrocyte progenitors. Protein quantification was assessed by immunoprecipitation and western blot analysis. To ensure specificity, congenic Cx32 null-mutant female mice were used as negative controls. To distinguish between the effects of estrogen and progesterone, we treated ovariectomized (OVX) females with 5 µg 17-β-estradiol. This concentration mimics circulating levels of estrogen in the proestrus range. Cx32 was visualized by immunofluorescence and colabeled with antigenic lineage markers.
Results: Cx32 mRNA and protein expression is suppressed during proestrus when estrogen and progesterone levels are highest and maximal during estrus when ovarian hormone levels are lowest. We confirm that within the hippocampus, Cx32 localizes to NG2-positive and PDGFαR-positive early oligodendrocyte progenitors as well as CNPase-positive oligodendrocytes in adult female mice. 17-β-estradiol suppressed Cx32 protein expression within six hours of administration in OVX mice as observed during proestrus in cycling females. Protein levels were restored 24 h after hormone replacement in OVX females as detected during estrus in cycling mice.
Conclusion: We show that Cx32 expression at both the mRNA and protein level fluctuates in the hippocampus of the brain and the T11-T13 region of the spinal cord over the course of estrous. These results demonstrate that ovarian steroid hormones specifically regulate Cx32 in the central nervous system of adult female mice.
|
| | |
| Back |
|
